#include <REGX52.H>
#include <intrins.h> 
void Delay(unsigned int xms)		//@11.0592MHz
{
	unsigned char i, j;
	while(xms--)
	{
		_nop_();
		i = 2;
		j = 199;
		do
		{
			while (--j);
		} while (--i);
	}
}

void main()
{
	unsigned char p=0;	
	while(1)
	{
		if(P3_1==0)
		{
			Delay(20);
			while(P3_1==0)
			Delay(20);
			p++;
			P2=~p;//p=0000 0000，p++=0000 0001 ，p2取反后p2=1111 1110
		}
	}
}